extjs extension lovcombo not showing checkboxes

I am using Ext.ux.form.lovcombo w/ Ext version 3.3.1

and I included

Ext.ux.form.LovCombo.css,
Ext.ux.util.js,
Ext.ux.form.LovCombo.js

I am not seeing any checkboxes when the combobox is dropdown, bu开发者_开发知识库t it seems to be functional, do I need to include anything more? What could be the reason for not seeing the checkboxes.

SOLVED: css paths were not correct for my ext installation.

.ux-lovcombo-icon-checked {
    background: transparent url('../images/default/menu/checked.gif');
}
.ux-lovcombo-icon-unchecked
{
    background: transparent url('../images/default/menu/unchecked.gif');
}

.ux-lovcombo-icon {
    width:16px;
    height:16px;
    float:left;
    background-position: -1px -1px ! important;
    background-repeat:no-repeat ! important;
}
.ux-lovcombo-icon-checked {
    background: transparent url(../images/checked.gif);
}
.ux-lovcombo-icon-unchecked {
    background: transparent url(../images/unchecked.gif);
}

/* IE patch */
.ext-ie .ux-lovcombo-item-text {
    position:absolute;
    left:16px;
    top:3px;
}
.ext-ie .ux-lovcombo-icon {
    float:none;
}
.ext-ie .x-combo-list-item {
    position:relative;
}